Conventionally, there has been a known technique for producing an electrode paste with good quality (i.e., homogeneous paste) using a twin-screw extrusion kneader. For example, the technique is disclosed in Patent Literature 1 described below, and is publicly known.
The conventional technique disclosed in Patent Literature 1 relates to a kneader (i.e., a twin-screw extrusion kneader) including a hollow barrel, and two rotary shafts provided parallel to each other at a predetermined interval in a kneading chamber formed inside the barrel. In the kneading chamber, a binder supply part, to which a binder is supplied, is disposed on the downstream of a powder supply part, to which a powder is supplied, in the conveyance direction of the powder, and a powder processing part having spacers, which are arranged on the rotary shaft and compress the powder, is disposed between the powder supply part and the binder supply part.
By producing an electrode mixture (electrode paste) using such a twin-screw extrusion kneader, it is possible to produce a paste with good quality (i.e., homogeneous paste).
Conventionally, in a case where the electrode paste is produced using the twin-screw extrusion kneader as described in Patent Literature 1, an inside of the twin-screw extrusion kneader is not airtight (i.e., the inside thereof constitutes an open circuit). Accordingly, before the electrode paste discharged from the twin-screw extrusion kneader is introduced to a closed circuit (defoaming tank) for performing vacuum-defoaming, the whole produced electrode paste needs to be temporarily received by the tank and subjected to batch processing.
Therefore, in the case where the electrode paste is produced using the twin-screw extrusion kneader, the time required to produce the paste becomes longer by performing the batch processing. Consequently, in the case where the twin-screw extrusion kneader is used, it is difficult to shorten the time required to produce the electrode paste.
The applicants have disclosed a technique on a system for producing an electrode paste combining a twin-screw extrusion kneader and a mohno-pump in Japanese Patent Application 2012-151920 (unpublished at the time of filing the present application).
By using the system disclosed in this Patent Application 2012-151920, it is not necessary to perform the batch processing on the electrode paste produced by the twin-screw extrusion kneader, and it is possible to continuously perform vacuum-defoaming in a pipe through which the electrode paste is conveyed to the defoaming tank, thereby shortening the time required to produce the electrode paste.